Adjustable thermostat



L. G. CUPEMAN.

ADJUSTABLE THERMOSTAT.

APPLKCATION FILED JULY 29. I916.

Patented Aug 10,1920.

lwuemtoz [Joyci Graf/ Copeman UNITED STATES VPA I'ENT OFFICE.

STOVE COMPANY, OF FLINT, MICHIGAN, A CORPORATION OF MICHIGAN.

ADJUSTABLE THERMOSTAT,

Specification of Letters Patent.

Patented Aug. 10, 1920.

Application filed July 29,1916. Serial No. 112,173.

To all whom it may concern:

Be it known that I, LLOYD Gnorr Corn- MAN, a citizen of the UnitedStates of America, residing at Flint, in the county of 1 Genesee andState of Michigan, have invented certain new and useful ImprovementsinAdjustable Thermostats, of which the following is a specification,reference being had therein to the accompanying drawings.

This invention relates to thermostats and refers more particularly to athermostat adapted to automatically control the temperature of anelectric stove or oven, although the invention in its broader aspects isnot limited to the particular use specified Amongthe objects of theinvention are to provide a thermostat which can be adjusted withoutcompletely disassembling the same; to provide a construction in whichthe thermostats attached to the various stoves can be adjusted to havesubstantially the same temperature readings; to provide a constructionin which the circuit is closed through an adjustable hand and a movablehand so arranged -as to permit the hands to pass each other when apredetermined temperature is reached, thus avoiding any strain on themechanism; .to provide a construction in which the thermostat can bereadily attached to the door or other part of the stove without thenecessity of exactly lining up the parts; to provide a constructioninwhich the necessity of insulation between the metal flange of thethermostat and the metal part of the door s avoided; to provide aconstruction in which the ad- 'ustment of the expansion strip iscontrolled y a cap screw which extends to the outside of the thermostat;to provide a thermostat of the character above referred to which can beeasily and accurately adjusted; and in general to rovide a new andimproved construction 0 thermostat.

The invention also resides in such features of construction andarrangements and combinations of parts as will more fully hereinafterappear.

In the drawings:

Figure 1 is a front elevation of a thermostat embodying my invention;

Fig. 2 is a side elevational view;

Fig. 3 is a cross section on the line 0ax of Fig. 2;

of Fig. 1.

Fig. 4 is a cross section on the line yg of Fig. 3;

Fig. 5 is a cross section on the line zz Describing in detail theconstruction shown in the drawings, A designates the door lining and Bthe flange of the thermo stat casing. This flange is carried by theoutside shell C which shell at its front end 1s provided with the usualmica disk D through which the dial E of the thermostat can be observed.An indicating segment F is arranged on the dial as shown in Fig. 1,across which move the ends of the hands G and H.

These hands carry cooperating electrical contacts G and H, theconstruction being such that the hand G can be adjustably set atwhatever point along the dial that will permit the contact H on the handH to contact with the point G on the hand G when the oven reaches thedesired temperature. When the circuit is thus completed the source ofcurrent to the oven or other device controlled by the thermostat wouldbe automatically shut off; the detailed construction of such circuit,however, forms no part of the present invention.

In actual practice it is found, there is a considerable. amount of heatin the oven which does not affect the thermostat until a few momentsafter the circuit is disconnected. \Vhere the hands are not allowed topass each other this places a considerable while they complete thecircuit when in mg I istration there is nothing but slight frictionalresistance to prevent the movable hand passing over the stationary orset hand.

By setting the stationary hand G at any desired point, the thermostatcan be set to shut off the current when any desired temperature isreached, this stationary hand being mounted on a shaft G which isoperated from the front of the casing by a button G v usted by hill) Themovable hand H is automatically ad the expansion of the bimetallic stripJ. Thus when the temperature 1ncreases sufficiently to expand the stripJ, 1t

' will rock the movable hand until the contacts 1 and H engage and shutoff the current to the stove. The strip J issecured at one end to anadjustable retainer strip K while its opposite or free end is connectedto a hnk it", the other end of which is secured to a cam or rock arm Lon the shaft L. The latter is rotatably mounted in a bearing L andcarries the movable hand H, there being a suitable stop L for limitingthe movement of the expansion strip.

Heretofore it has been necessary after the thermostats have once beentested andadjusted, to subsequently adjust by bending the expansionstrip so as to relleve or mcrease the tension of the strip. Thereforeafter the thermostat was installed in the door, further adjustment wasimpossible without completely disassembling the thermostat forreadjustment. In the present construction thisobjection is not onlyovercome but the adjustment can be made from a point exterior of thecasing.

-As shown in detail in Fig. 3, the adjustable retainer strip to whichthe expansion strip is secured has a set screw M projecting outwardthrough an elongated slot M in the casing. A suitable lock washer N, andbrass and mica Washers N and N are provided, the arrangement being suchthat the set screw M can be loosened and the retainer strip shiftedaround the casing to place the desired strain on the expansion strip,after which the set screw is tightened up to lock the-retainer strip inat the adjusted position. By this arrangement it is possible to adjustthe various thermostats after they are inplace so that the temperaturereadings for the various thermostats will be uniform. The amount ofadjustment forward and backward for the movable piece, or retainer stripM is suttic ient to permit any desired adjustment within a range of over200 of heat.

The operating or interior mechanism is carried by a retainer ring Uwhich is insulated from the shell or casing U by suitable micainsulation 0'; The ring 0 has an elongated slot li cut therein, toreceive the strip K, the circumferential length of the slot K beinggreater than that of the strip K to permit of the adjusting movementdescribed above. This operating or interior mechanism acts as one polefor the circuit to the hands, .while the hand G acts as the other pole.The lead to the hand G is through the brass terminal strip P whichextends through an opening P in the shell C, and is insulated therefromby insulator strips P while the lead to the other pole is through a postQ extending through and insulated from the shell. This arrangementwhereby the shell and. its base flange are insulated rangement whichwill permit the base of the thermostat to be securedto the door, even ifall the parts do not happen to exactly line up. For this purposetheflange B is pro- .vided with projections R and R which have apertures Sand S of considerably 'reater size than the diameter of the screws T andT. Adjusting plates U and U are fastened to the 'PI'OJGCtlOIlS R and Rby securing members U and U these adjusting plates being screw threadedand acting as a nut for the screws T and T. As the front of thethermostat is sometimes covered by an escutcheon which is also heldinpermanent position by screws, it has heretofore been impossible to getthe escutcheon in place without practically disassembling the door forrealinement. In the present construction the thermostat can be fastenedto the door and the screws T and T left somewhat loose so as to permitthe thermostat to be moved in any direction to line the base upcorrectly with the escutcheon, after which the screws can be tightenedup from the inside of the oven.

A. thermostat constructed as above described can be more convenientlyattached to its support than previous thermostats of this type, and thetension of the expansion strip accurately adjusted withoutdisassemever', is not limited to the particular constructions shown forobtaining these advantages except as specified in the appended claims.

What it claim as myinvention is: 1. In a thermostatic circuit-closingde; vice, the combination with a casing, of mechanism within the casingcomprising a ring co-axial with said casing, thermostatic means in'saidcasing, a pointer actuated by said thermostatic means and adapted to actas one of the terminals of an electric circuit, adjustable supportingmeans for said thermostatic means, insulation between said ring and saidcasing, a manually adjustable arm cooperating with said pointer andadapted to act as the other terminal of an electric circuit, andinsulation between said arm and said casing. v

2. In a thermostatic circuit-closing device the combination with acasing and a dial thereinjof a ring mounted in said casing and co-axialtherewith, insulation be- 'bling the thermostat. The invention, howtweensaid ringa'nd said casing, a bracket therefrom and circumferentiallyadjustable therein, an adjusting member extending through said casingfor adjusting said supporting member, a manually adjustable armcooperating with said movable pointer to close an electric circuit underprdetermined temperature-conditions, and insulation between said arm andsaid casing. I v

3. In a themostatic circuit-closing device, the combination with acasing, a dial therein, a ring mounted in said casing coaxial therewithand adapted to forni one terminal of anelectric circuit, and insulationbetween said ring and said casing, of a terminal member adapted to ,formthe other 1 terminal of an electric circuit, insulation between saidterminal member and said casing, a manually adjustable -arm locatedwithin said caslng and connected to said terminal member, thermostaticmeans in said casing, adjustable supporting means for said thermostaticmeans, and a pointer actuated by said thermostatic means and cooperatingwith said manually adjustable arm to close an electric circuit at apredetermined temperature.

In testimony whereof I afiix my signature in the presence of twowitnesses.

LLOYD GROFF COPEMAN.

Witnesses:

DAVID W. OVAR'I'I, S. S. HOWARD.

